Yesterday I read about a open source project used for testing Web Services. It was a discussion thread at a LinkedIn Group. Someone asked everyone to list their favorite automated testing tools.
This utility is called soapUI. I recommend it for testing web services. Here's what I have done with it so far; create a new project, point to the WSDL, generate the test suite and mock service, edit a request, and then submit request to the endpoint URL.
It reminded me how I learned software testing. I read books, articles, forum posts, and try all kinds of tools, utilities, and scripting languages. I'm still learning all the time.